A method for use in preparing mixed pickles by using three-stage fermentation using a liquid which is flavored with fruits and vegetables used in Traditional Chinese Medicine and by using positive and negative pressure coordinated permeation technology: the raw flavor of a raw material being removed by means of hot water processing; using a drying machine having an intelligent air source heat pump to perform two-stage moisture removal and two-stage drying to obtain a dried raw material; performing low-temperature pickling at 4–5°C before fast freezing; placing said dried raw material in a freezer for freezing and pickling; using a fermentation liquid flavored with fruits and vegetables used in Traditional Chinese Medicine to permeate the frozen raw pickle material under the conditions of positive and negative pressure coordinated processing; first performing two stages of positive and negative pressure permeation on a tuber raw material; adding and mixing a solanaceous raw material and performing one stage of positive and negative pressure permeation; lastly adding and mixing a leaf vegetable raw material and then performing one stage of positive and negative pressure permeation; non-destructive sterilization being performed under super high pressure to obtain a mixed pickle product. By means of said method, a mixed pickle product which has a harmonized taste and which is more similar to traditional fermented pickles may be prepared, having no raw flavor, having low nitrite content and having high production efficiency.